December Birthstone: Turquoise, Tanzanite & Zircon
December is the rare month with three official birthstones, all of them blue. Here is how turquoise, tanzanite and zircon differ in colour, durability and care, so you can pick the right one.
Key Takeaways
- December has three official birthstones: turquoise, tanzanite and zircon, all recognised by the GIA. Blue topaz is a popular informal addition.
- They are very different stones. Turquoise is an opaque blue-green; tanzanite is a transparent blue-violet; zircon comes in many colours but blue is the December favourite.
- On the Mohs hardness scale, turquoise sits around 5 to 6, tanzanite around 6 to 7, and zircon around 6 to 7.5, so none of them is as tough as a sapphire or diamond.
- Tanzanite and turquoise both need gentle care. Skip ultrasonic and steam cleaners; warm soapy water and a soft cloth are safest.
- For everyday rings, choose a protective setting. For pendants and earrings, all three wear beautifully with little fuss.
What is the December birthstone?
December's birthstones are turquoise, tanzanite and zircon, the three stones listed by the Gemological Institute of America. It is one of only a handful of months with more than one official stone, and what ties them together is colour: all three are best known in shades of blue. Many jewellers, ourselves included, also count blue topaz as an unofficial fourth option because it is affordable and easy to find. So a December baby has real choice, which is unusual.
The catch is that these three stones are not interchangeable. They sit at very different price points, they handle daily wear differently, and they look nothing alike up close. Picking the right one is less about which is "best" and more about how the piece will be worn.
Turquoise, tanzanite and zircon compared
Here is the quick version before we get into each stone. Hardness figures below come from the GIA and the International Gem Society.
| Stone | Typical colour | Mohs hardness | Transparency | Best for |
|---|---|---|---|---|
| Turquoise | Sky blue to blue-green, often with matrix veining | 5โ6 | Opaque | Statement pieces, pendants, protected rings |
| Tanzanite | Blue to violet-purple | 6โ7 | Transparent | Earrings, pendants, occasion rings |
| Zircon (blue) | Bright sky blue (also colourless, red, brown) | 6โ7.5 | Transparent, very brilliant | Rings, pendants, sparkly everyday wear |
Turquoise
Turquoise is the oldest of the three by a long way. It is a semi-translucent to opaque stone in blue to green, usually with darker veins of "matrix," the host rock it formed in, running through it. According to the GIA, the most prized colour is an even, intense robin's-egg blue. Because it is porous and on the softer side at 5 to 6 on the Mohs scale, turquoise can absorb oils, lotions and perfume over time, which dulls the colour. Keep it away from chemicals, put it on after you've done your hair and makeup, and wipe it with a soft dry cloth. It makes a gorgeous pendant or pair of earrings and a fine ring if the setting protects the edges.
Tanzanite
Tanzanite is the new arrival. Prospectors located the main source in 1967, and the GIA notes the Merelani Hills of northern Tanzania, in the shadow of Mount Kilimanjaro, are the only place on earth where it is mined commercially. That single source is part of why people love it. The colour is a deep blue that shifts toward violet depending on the light, and a clean tanzanite has a glow that few blue stones match. The trade-off is durability. At 6 to 7 on the Mohs scale it scratches and abrades more easily than sapphire, and the GIA is clear that tanzanite can crack with sudden temperature changes, so you should never use ultrasonic or steam cleaners. Clean it with warm soapy water and a soft brush. We usually steer customers toward tanzanite pendants and earrings, or a ring with a protective setting that they won't bang around every day.
Zircon
Zircon is the most misunderstood December stone, mostly because the name sounds like cubic zirconia, which it is not. Natural zircon is a real mineral, and it has more fire and brilliance than most coloured stones, so much so that colourless zircon was confused with diamond for centuries. Per the GIA, it occurs in red, orange, yellow, brown, green and blue, but the bright sky-blue is the one people associate with December. At 6 to 7.5 on the Mohs scale it is the hardest of the three, so blue zircon handles ring wear better than turquoise or tanzanite. One thing to know: zircon can chip or abrade at facet edges, so a setting that tucks those edges in helps.
Care: the soft-ish stone problem
None of December's birthstones is a tough everyday workhorse like a sapphire (which sits at 9 on the Mohs scale). That doesn't mean you can't wear them, it just means setting and habit matter. On our Coquitlam bench we set tanzanite and turquoise in bezels or with raised side prongs that shield the stone, and we always tell customers to take rings off before gardening, cleaning or the gym. For all three, the rule is the same: warm water, a drop of mild dish soap, a soft brush, then pat dry. Leave the ultrasonic machine for the diamonds. If a tanzanite or turquoise piece has lost its shine, bring it in and our goldsmith can clean and recheck the setting in person rather than risk a home cleaner.
Choosing a December gift
If the gift is for someone who wears jewellery hard, blue zircon or blue topaz is the practical pick. If they love a distinctive colour and will treat the piece gently, tanzanite is the showstopper. If they lean toward an earthy, vintage or bohemian look, turquoise is unbeatable and reads as far more personal than a generic blue stone. Pendants and earrings open up every option because they take almost no knocks. We design and make these in-house, so if you want a specific shade of blue or a setting built for daily wear, we can build it around the stone rather than forcing the stone into a stock mount.
Want to go deeper on the stones themselves? Read our guide to gemstones, or if a diamond is on the cards instead, our guide to diamonds covers cut, colour, clarity and carat.
Frequently Asked Questions
What is the official birthstone for December?
December has three official birthstones: turquoise, tanzanite and zircon, all listed by the GIA. Blue topaz is a common unofficial addition. They are all known for their blue colour, which gives December babies more choice than most months.
Which December birthstone is best for an everyday ring?
Blue zircon is the hardest of the three at 6 to 7.5 on the Mohs scale, so it holds up best to daily ring wear. Blue topaz is also a sturdy, affordable choice. Tanzanite and turquoise are softer and better suited to pendants, earrings, or rings with a protective setting.
Is tanzanite a durable stone?
Tanzanite is moderately durable, about 6 to 7 on the Mohs scale, which is softer than sapphire. It scratches and abrades more easily and can crack with sudden temperature changes, so the GIA advises against ultrasonic and steam cleaning. With a protective setting and gentle care it makes a lovely occasion ring and an easy pendant or pair of earrings.
Is zircon the same as cubic zirconia?
No. Natural zircon is a genuine mineral with strong brilliance and fire, and it has been used in jewellery for centuries. Cubic zirconia is a man-made diamond simulant. They share a similar-sounding name but are completely different materials.
How do I clean turquoise jewellery?
Use only warm water with a little mild soap and a soft cloth, then dry it gently. Turquoise is porous and can absorb oils, perfume and lotion, which dulls the colour, so put it on last when getting ready and keep it away from chemicals and ultrasonic cleaners.
Why does December have so many birthstones?
Birthstone lists have been revised over the years as new gems were discovered and trade groups updated their recommendations. Tanzanite, for example, was only added after its 1967 discovery. The result is that December now carries three official blue stones plus blue topaz as a popular extra.